The invention relates generally to laser cutting systems and deals more particularly with a means for delivering sheet material to a support surface where it is cut into pieces and for removing the cut pieces.
Laser cutting systems of the type with which this invention is concerned are capable of cutting sheet material accurately and rapidly. Such a system often includes a worksheet supporting surface, a laser cutter for cutting the sheet material, and a computer which controls the laser cutter. The support surface is designed to minimize back reflections of the laser beam of the laser cutter and to endure the laser beam itself. Laser cutting systems are often equipped to cut only one worksheet at a time and so, to increase the output of the system and to minimize the amount of human labor required to operate the system, it is important to provide a means for automatically delivering uncut sheet material to the support surface and for automatically removing the cut pieces. Also, it is important that the sheet material be delivered with few wrinkles.
A laser cutting system of the type with which this invention is concerned is disclosed in U.S. Pat. No. 3,755,861 to Castro et al. There, a worksheet supporting surface is formed from a plurality of honeycombed elements mounted on an endless conveyor belt. The honeycombs are open at the top and trap laser beams incident thereto to prevent harmful back reflections. A roll of sheet material to be cut is mounted to rotation above the bed and displaced longitudinally a few feet back from the receiving end of it. The sheet material is drawn from the roll downwardly into a slack loop by a soft wire roller which engages it beneath the roll. From the slack loop, the sheet material extends upwardly onto a highly polished, chute which guides it onto the endless conveyor. As the endless conveyor turns, the sheet material is drawn by friction from the slack loop, onto the worksheet supporting surface and downstream to a cutting location on the conveyor belt.
The honeycombed structure of the U.S. Pat. No. 3,755,861 belt is not disclosed in detail; however, a belt possibly of this type is shown in U.S. Pat. No. 3,828,697 to Egan. The U.S. Pat. No. 3,828,697 belt is rather complex and includes a plurality of slats assembled into an endless conveyor belt with the honeycombed elements being mounted on the slats.
A general aim of the invention is to provide a means for automatically feeding sheet material to a laser cutter reliably and without much wrinkling.
A more specific aim of the invention is to provide means for automatically feeding bites of limp sheet material and accurately tracking the sheet material as it is fed so that pattern pieces which overlap two or more bites may be cut accurately.
Another general aim of the invention is to provide such a feeding means which cooperates with a worksheet supporting bed having a more simple construction than that of a honeycombed bed.
Another general aim of the invention is to provide a means for automatically removing cut pattern pieces and scrap from a cutting region of the foregoing worksheet supporting bed to more fully automate the cutting process.